Apparatus for treating strip steel



April 15, 1941. c. c. WALES APPARATUS FOR TREATING STRIP STEEL Filo d Oct. 20, 1937 :s Sheets-Sheet 1 INVENTOR. 01 421.55 (AFR/(E hf/uzs' M ORNEYS April 15, 1941. c, c, WALES 2,238,667

Afi'ARATUS FOR TREATING STRIP STEEL Filed Oct. 20, 1937 3 Sheets-Sheet 3 iu t8' INVENTOR. 01/7/2455 (Ame/(5 M455 A'fTORNEY6 cause' such would interfere with pulling through The trailing end of each stripis-usually-tied t the leadingjend of another as by'the'useof man appliedjacid resisting hooks'o'r'other tying f devices and; since the stock is relatively light in Patented Apr. 15, 1941 Application October 20, 1937, Serial No. 170,038

2 Claims. (01.29-33) This invention relates to apparatus for'handling sheet steel, particularly in the. continuous v pickling of hot rolled strips; Certain principles.v hereof are ,also applicable in connection with other treating and/or fabricating operationson sheet or strip steel, for exampl'e', annealing, tem-' pering and whatever otherloperations can be per- I stock, the more difllcult it becomes to tie the "trailing end of one strip to the leading end of another in the manner practically necessitated by the use of a pull-through type of apparatus.

Speed capacity of pull-through types is also limitedby the strength of end-to-end connections formed on strip steel while advanced-continuously or in successive steps.' 1

At the present time there are in operation two types of ,continuous strippicklers:, (al'thesingle' strand" or pinch-roll-controlled type of unit, used principally for-pickling scale from hot rolled strips in single; strands in widths from 22" to 96"; and in thicknesses from sz" to 1"'-at speeds from twenty live. to one hundred and seventy fl ve feet per minute, de'pendirigupon' the numberof acid tanks: and .(b) multiple strand type, units, used principally for pickling several strips side-by-side, say from two to. eight or more separate strands .at a time. ,"I'ype "b is principally .use d in pickling strip fi om two inches up e ty nches in Width, an r m om"; to

.080" thick. Thepresent invezr tiimrelates to the" 7 handling of strip stock asin'Type inf-{although .11; enables multiplestrand treatment to bejeffect- 611 8-3 will later'be shown being made i to level the stock, principally; be.

weight and' flexible, the workmen are able to eflect tyingtogether of the trailing and leading ends and removal of the tying devicesras necessary, without having to-provideintermittently operable feeding means to assist in applying and, subsequently, removing the fastening or tying means. 1 I

.Such multiple strand. type (pull-through) apparatu's, as faras I" am aware,.has never been so arranged that the feeding devices, for the-individual "strips can operate on a single strip "which in width approaches the maximum width capacity 01' the unit. It would seem that the pulling mechanism a could be rearranged and adapted to handle strips of any width capable of entering the pickling tanks; but, in connection on widths and thicknesses greater than the maxima above indicated. For instance, any strip wider than 20" would be naturallyunwieldly and difllcult'to manage, even though the stock is comparatively thin. The wider or heavier the on the equipment.

between strips; forfif the tank length is great enough to allow substantial increase of strip' speed '(must then be lengthened to maintain necessary immersion period), the connections are apt to fail. Moreover, a strip as thick as 5" usually develops coil breaks as itleaves the supply coil (has scallop formation as viewed edgewise). Obviously a wide or heavy "sheet that has developed coil breaks would be difllcult to move over the carrier rollers, across 'the bottom surfaces of the tanks, and past the usual depresser rolls which assist in maintaining proper immersion, and would cause rapid wearing and strain The above discussion of the usual multiple strand .unit type of apparatus, is m, order that the. present subject matter will not be confused -.therjewith, and in order that the problems solved Y with the handling of material which is wider or thicker tharrcan be effectively handled on mule multip s a d n 1 P QPP C'J tice hasbeen to drawthe strips oilfithefeedreels and through-the acid tanks by recoili'n'g apparai I tus-at the deliver'yflend of the'system; no attempt tiple strand type apparatus as heretofore used) tus which will operate efliciently to treat ;and

. reee fairly heavy gauge strip steel either in a ;single. strand or strip, as wide as can pass throughthe elements of the apparatus, or (in- .terchangeablyl at least two relatively narrow non-'over-lapping strips of any total width under ,such predetermined maximum, and, specifically,

to provide animproved system, apparatus and mechanism for pickling sheet steel in substan-' tially continuous strip form.

A further specific object is to provide a sheet pickling system of the pinch-roll controlled type, which will operate efficiently, interchangeably, on

wide and narrow sheets.

Another object is to provide for increasing the -efliciency and operative capacity. of continuous of the stock through the necessary feeding,

shearing, stitching and unstitching units .and essential treatmentmeans may be greatly speeded up, as compared to present practice,

The provision of an apparatus wherein wide and'narrow sheets may be treated interchangeably at speeds comparable favorably with those now used in single purpose treating plants, (single strip or multiple strip) or at higher speeds, requires wider spacing of operating units. as between the initial stitch control feeding and the feeding means which further advances the stock to the zone of essential treatment oi the strip (such as pickling); and a further specific object is to provide such increased spacing without having to increase the size of buildings now adapted for such treatment; without reduction in scale of the necessary apparatus; without having to effect relatively expensive changes in the equipment used; and without having to provide outbuildings for accommodating any of the mechanisms included in the system. Ancillary objects, in line with the above, include the provision of an improved looping arrangement for stock between diflerent feeding mechanisms.

Other objects and features of the invention will become apparent from the following description relating to the accompanying drawings which show the preferred arrangements and constructional features incident to carrying out the method.

Referring to the drawings, Fig. 1 is a more or less diagrammatic side elevation of the apparatus arranged for pickling hot rolled strips; Fig. 2 is a similar view, showing an alternative arrangement for the same purpose, portions of the pickling tanks in both figures, being broken away, to enable showing the entire system in single views; Fig. 3 is a plan view of the arrangement, according to Fig. 2,11. being understood that, in general, a plan view of the Figure 1 arrangement would be substantially the same as a plan of Fig. 2 except that the order of placement of initial feeding and fabricating mechanisms, shown at the right, is reversed; Fig. 4 is a plan view of a pinch roll mechanism and also a portion of one of the pickling tanks and a dancer mechanism operating therein to control the speed of one set of pinch rolls; Fig. 5 is a view similar to Fig. 4, showing the efiects of adjusting the pinch roll and dancer mechanism for pickling single sheets; Fig. 6 is a sectional view, through the pinch roll mechanism, as indicated by the line 66 on Fig.

4; and Fig. 7 is a front elevation and Fig. 8 a

from a direction transverse to the direction of feeding strip through the system, as on a standard double inclined roller conveyor, shown at i. The coils may be moved oil the conveyor, as to the position A and the free edge of the strip in feeding position is passed between the rolls of an uncoiler and leveier mechanism 2 of any known or suitable form, adapted to remove the coil breaks from the stock, level it, and advance the leading edge to a cropping sheer mechanism or other cropping means indicated generally at 3. This may be arranged as an up-cut or down-cut shear, and operates to sever the irregular and (formed in the usual hot rolling process) from the strip. The strip is then passed to a stitching mechanism 4; and assuming another strip has preceded the one under discussion, the tail mechanism d.

asses? end of such preceding strip is'held at the stitcher until the leading end of the new strip is advanced over it to stitching position. The detailed construction of the shear 3 (or a suitable form of such) which construction may also apply in a general way to the stitcher 4, will be later do scribed. Usually the stitcher operates by punching through portions of one strip into interlocking relation to the other, as is well known. Instead of stitching in the manner indicated, spot, line or butt welding may be used to attach the extremities of the strip together; and as used herein the term "stitching or stitching mocha nism includes welding, and any other way of fastening strip stock sections in end-to-end relationship.

From the stitching mechanism 3 the stock passes through a pinch roll stand 5. This is principally useful in controlling the position of the tail end of such preceding strip, as above mentioned, with reference to the stitching 3 when such tail end passes said mechanism. The strip passes from the pinch roll stand 5 over a looping space which may be in the form of a pit t, to a second pinch roll stand 1. The loop in the stock is diagrammatically indicated at B.

A suitable construction of the pinch roll stands for interchangeable use on wide and narrow strips, will be hereinafter fully described, which construction may also apply to a final pinch roll. mechanism at the delivering end of the pickling system. The controls for the two stands 5 and l difi'er-in that the stand 5 is controlled manually, since the stitching and cropping ordinarily would be controlled manually, whereas the stand E preferably is controlled by a dancer mechanism, including a dancer roll it, which rests on top of the strip or strips being advanced by the pinch roll stand l over a carrier roll 9 at the entrance to the first tank id in case there are a plurality of tanks.

The dancer roll, controls, as by a suitable rheostat or rheostats, the speed of operation of the stand 1, and this maintains the proper amount of sag in the tanks. The provision for the slack or loop, such as B, in the stock between the pinch roll stands 5 and l, is in order that pickling may proceed at a uniform rate notwithstanding stoppage of portions of the strips for cropping and stitching. Temporarily, after stitching, the rolls of stand 5 are speeded up until there is a safe amount of slack between the stands 5 andl, sufiicient to avoid pulling the stock in two, or damaging the pinch stands and to avoid pickling time loss; and then, until the next cropping and stitching operations are performed the two pinch stands may be substantially synchronously driven.

The dancer roll 8 operates substantially in the usual way to control the pinch roll speed; the operation however being modified in order that either one or two sheets can pass through the system, and, in case there are two, that these can move independently of each other. strip tightens and tends to rise from the first tank, it raises the dancer roll. and this, in tum, speeds up the rolls of the stand 5 until the dancer roll or rolls again assumes or assume normal posttion, in which the strip or strips at C is or are again properly immersed in the solution contained in the tank.

The strip then passes froni tank" to tank over rubber covered carrier rolls 82 (only one set The tail end of such preceding sheet is (or can be) cropped, as by the mechanism.

Asthe' stand I. i tioned, i. e., l to 5, can be placed below thefioor,

shown) between adjacent end Walls of adjacent,

tanks, finally emerging" fr'omthe last tank over a rubber covered carrier roll. l3. There may, of course, be any number of tanks, say from two to eight. A plurality of tanks are used partly because raising the stock periodically from the pickling solution hastens pickling, and precipitation of. loosened scale from the stock. i

The pickled stock, after it passes overthe final carrier'roll I3, is'drawn, as by a pinch rollstand Is at the. delivery end of the pickling plant, through a scrubber I6, which may be of any type,

and then through a drier mechanism having 'portions l1. and I8. The construction of the stand mechanism may be same aslin case ofstands 52111111.

Preferably the scrubbin'g 'a nd drying is done partially mechanically as. by; reciprocating or In one arrangement (strip looping substantially the stock passing over a suitables lpporting roller 29, in line with the first "pinch stand, and

thence downwardly into a looping pit 3 0, preferably built as a tank, tocontain water. The stock of the loop passes upwardly from the pit and over i a suitable guiding roller 3| to the underpass.

rotary brushes, and partially by hot-water or,

steam or both, the heat applied beingimportant in order to effect drying. Suitable air blasts may also be used; it beingimportantithat-the stock be fully dried before recoiling beyond-the pinch rollstand |5.' r v As the stitched portions of the various strips pass beyond the stand IS, the ieeding operation of the rolls of the stand I5 is interrupted for a Near the top of the pit, and in the region in I which the loop of the stock engages the supporting roller 3|, I preferably provide a baflle 32, ex-

tending clear across the pit, which holds back any scum which ma'yjaccumulate on the outer portion of thelpit, wherefore, as the stock leaves the pit, it willpass out of relatively clean water and carry less foreign material with it than suificient period to' allow the stitched portions to be sheared out, as'by a down-operating shear 20, having a double knife adapted to cutthe overlapped and stitched ends of thestrips simultaneously, and to discharge the severed sections out ciple as the shear 3 and stltcher '4.

The pickled stock is finallyrecoiled, as in a' coiling unit 2|, which operates similarly to the uncoiler 2, but me reverse direction. The stock being recoiled, is indicated at D. Such recoiling unit ispreferably of the three-roll type, either lip-coiling or down-coiling, although, alterna-' of the way. The construction of the-"unstitching shear mechanism may be the same in printively, the stock may be'taken 01f onto a drumtype reel. From the recoiler unit, the coil is dis- 1 charged away from the pickling system, as on a conveyor 24, operating transversely of the line of progress of the strip orfstrips through the-plant.

It is common practice in recoiling to oil the strips for cold rolling or for protection when being shipped to customers, as hot'rolled pickled coil. i

A variation in the general arrangement'above roll, in'a direction reverse tothat of the progress of the stock through the pickling tanks. In other wordsflthe direction of movement of the stock-is reversed between the first and second pinch roll stands. order to provide additional looping space, in the event of feeding two strips of stock, and therefore having ,to effect cropping and stitchin .at

more frequent intervals than when running through af'single strip. The various mechanisms are numbered the same as in Fig. 1, it being noted that the uncoiler, shear, stltcher and fir'st tackle, right inside the plant building. Incase described is shown in Fig.2. This variation, in general, refers to feeding the stock through the uncoiler, cropping shear, stltcher and firstspinch' would otherwise be the case; Heat is maintained in the water of the pitby any suitable means. In'addition to cleansing the stock, heating of it enhances the pickling process (enables faster pickling speed) without having to increase pickling tank capacity.

In readapting existing plants to use the system shownin-Fig. 2, it isunnecessary to enlarge the buildings in order to obtain greatly enlarged looping space-mother words, a much greater amount of slack. between the two pinch roll,

stands, such as 5' and 1. In case the loop extends outwardly as'at E, a relatively small opening may be .made in the building wall' and any suitable inexpensive shed placed over, the area'into which the loop extends. To avoid fouling I propose. toemploy means to pull out the loop or loops, such 3 as cars R, Fig. 2, on tracks inclined. downwardly away from the-plant proper, and having arms, rollers or bails S to engage the loops. Either such cars or the loops could be biased in'the proper direction by any convenientcounterweight or spring operated system. Alternatively the loops could b hoisted by counterweights on suitable thel'looping pit is used, this may be installed either in the main building or outside it under inexpensive shedding.

Referring now to the plan view of the appara{ tus and system shown in Fig. 3, it will be noted that there are two strips of material being treated, which'strips pass through all the mechanisms comprising the system, includingthe two acid The reason for this arrangement is in stltcher, croppin ,shear and unstitcher.

tanks shown in side-by-side and spaced relationship. To accomplish this, it is necessary, individually, to drive the two stripsat ,all the pinch roll stands,- and individually to operate the The uncoiler and leve er and the. recoiler rolls may Ya-lso'be individuallydriven as to the two portions stand; are located in a plane above the floor level,

indicated at L. There is an, underpass "P, by

' which' the stock can return, below the various mechanisms mentioned, to the second 1 pinch Alternatively, the mechanisms menand the loop then passed above said mechanisms to the stand I.

Two methods of looping are indicated on Fig. 2.

, Figs. 4 to 8, and the same arrangement operatestofeed, crop, stitch and shear a. single strip the I ofe'ach unit-which act on respective strips. I- have arranged' for individual treatment of'narrow strips as will be described in connection with width of which may-be as great as the combined maximum width of the two strips shown in Fig.

3, including the intervening spacebetween such two strips. 5 I r When working a single strand pinch-roll-controlled pickler it'is customary to speed up the rollers 26 and N, to the-pinch, I

' and the recoiler.

recoiler (as 2!) after shearing out the stitching, sothat the recoillng of the strip may be finished and the coil discharged away from the pickler before the on-coming coil end of the next strip reaches the rec'oiler. This speeding up of the recoiler is impossible in the present therefore proposed, to avoid difllculties, that the finished coil be ejected as shown in Figs. 1 to 3, toward the discharge end of the pickler, onto the conveyor 24 over a table between the shear Thus, it is possible to pickle material in single strands in the same manner and throughout the same width and gauge as by standard pinch-roll-controlled types of picklers, many of which are now in operation. It is also possible to pickle two strands at a time in widths slightly less than half of the maximum single strand pickling width and the production efficiency is increased to a very large extent on the 1 narrow material.

Specific mechanisms The general principle of operation of the various pinch roll stands is the same; additional refinements being provided to control, automatically the second pinch roll stand I, as shown on Figs. 4 and 5'. The two shearing mechanisms and stitchers all may be operated on the same general principles, which will be described in system when pickling two strands, and it is connection with Figs. 7 and 8. The specific showing of shearing mechanism of the latter figures is that of the double shear mechanism 20, for removing the stitched overlapped ends of two or more strips.

. Referring now to Figs. 4, 5 and 6, the Pinch roll stand shown, has heavy side frames 10, carrying upper and lower pinch rolls 4| and 52. The rolls are split in the center in case it' is desired that the two narrow strips of stock to be treated interchangeably with one wide strip are may be split at any other point intermediate of the two frames, should it be desired to run a strip wider than half the total width capacity of the' various mechanisms, together with a strip materially less'than half such width.

As shown in Fig. 6, the roll sections Ma and 42a, lib andv 42b have driving shafts 4 5, journalled in appropriate relatively adjustable bearof substantially equal width. However, the rolls aesaccv An appropriate means for supporting the inner ends of the roll sections Ma and 41b, 42a..

and Mb, may comprise providing, on one of each pair of aligned sections, as Ila, a heavy pilot extension 51, having spaced bearings 58 in an axial bore 59 of the other section of such pair. One extension 51 projects to the right and one to the left, in the particular arrangement shown.

When using the system for conveying two strips, the roll sections at each side are independently driven,. that is, started and stopped, speeded up or slowed down in accordance with operating conditionarequisite to the individual strips, but when feeding a single wide strip, which, bridges the two roll sections, it is then practically essential that the aligned sections operate as a unit. To accomplish this, the sections may be simply pinned together at their telescoping regions, as by removable pins 60, shown only on Fig. 6. A more quickly operable connecting and disconnecting means may be provided between the sections of each roll, or at least the sections of one of the rolls; for example, a dental clutch, not shown. I also contemplate synchronizing the driving motors of the driving mechanisms on each side, so that no positive interconnection between the roll sections would be necessary to cause them to operate, in eflect, as single upper and lower pinch rolls.

Referring particularly to Fig. 4, a spacer or center guide 62 is provided between the two strips of stock, in order to prevent the edges of either strip from spanning the break in the roll. This center guide may be removably supported, preferably by the pinch roll stand frame in suitable fashion, and is removed when using thesystem for a single wide strip. Side guides 64 for the extreme edges of the strip or strips, passing through the stand, may be adjustably mounted on appropriate guideways, and their positions adjusted by right and left-hand screws, as usual.

Figs. 4 and 5 show the dancer roll arrangement, which I propose to useat the entrance to the first acid tank, to control the, speed of the pinch rolls of the stand 1. This comprises, preferably, sectional shaftingextending across the tank and supported, as on its top wall. The shaft section 65 extends within the section 66, which is hollow, and the two sections 65 and 66 may be secured together as by a pin 51 or any suitable clutch arrangement (not shown). Parallel arms 68, on respective sections of the shafting, support the dancer rolls 8, heretofore mentioned. These rolls ride'on the strip or strips, as the same passes or pass into the tank. When operating on two strips, the dancer rolls operate The specific driving arrangement for the shafts 45 illustrated, comprises a housing 52 for permanently meshed gears 53, drivingly rigid with respective shafts 45, one of the gears being permanently connected to a reduced gearing mechanism 55, operated by an electric motor 56. The drive for the sections Nb and 4212, which are at the left in all figures, may be identical with thecdriving mechanism shown at the right in Fig. 6 and just described. Each driving mechanism has its own'motor. The control for the motors may be manual or automatic, 1. e. governed by the work, as in case of the dancercontrolled pinch roll stand I.

individually to turn the sections 65 and 66, which in turn, through any suitable means, govern respective controllers for the motors 56,. As shown, motor field rheostats 69 are indicated diagrammatically, and the control connection, with the shafting may comprise contactor arms l0 'secured to respective shaft sections 65 and 56 and adapted to contact successively with the rheostat points ofv respective rheostats. By this means, if two sheets are being run, the opera tion of the pinch rolls driving one strip is independent of the operation of the other. It would probably not be necessary to connect the shaft sections 65 and 68, together, for single sheet control, if the stock were truly uniform transversely of it. When this is not the case, I provide for connecting the dancer roll frames to insure their unitary operation on a single sheet,

irrespective oi transverse non -uniformities of stock.

It will be understood that in the case of the first pinch roll stand this is not provided with any arrangement similar to the dancer roll hook-up described, but there .the motors are controlled either individually or together, as by the workman in charge of cropping and stitching; independent or single control being used in connection with running two sheets and one sheet, respectively, as will be obvious from the above description.

The shearing unit (for instance unstitching unit 20) which is shown in Figs. 7 and 8, repre sents a known type of mechanism, wherein the shear blades are appropriately split and usable individually or together, for multiple-strip and single strip fabricating, respectively. If the endwise adjacent strips are to be interlocked togetherg to stitch them, then the same general design of machine can be used for stitching, simply by changing the tools from shear blades to stitching dies of known or suitable form.

In Fig. 7 the general framework of the ma chine is indicated at 15, the main power shaft 16 being appropriately journalled on the frame sides, and controlled manually in a well known manner by a single rotation clutch mechanism 18a. The shaft 16 has crank portions operating to reciprocate connecting rods l1, one being shown on each side of the machine in Fig. -'l. The rods, in turn, reciprocate the upper part 18 of a sectional crosshead, slida-bly mounted on appropriate guides at opposite sides of the frame. Two sets of movable shear blades 80 and N, are supported individually by lower crosshead sections I9 spaced from the upper sections and normally out of the range of movement of said upper sections. The lower blades 82 may be fixed and each made as single sections or in as many sections as desired.

In' the arrangement shown, the power shaft turns once to effect cutting of strip stock by the blades, and either blade 80 or 8| may be'lowered to effect cutting, or both may be lowered together. The selective operation is under the control of lever arms 85 and 86, which are operatively associated with the blade sets 80 .and 8|, respectively, through telescoping shafting.

The sections of the shafting are indicated at 8| and 88, and these are turned bythe arms 85 and 86. When the arms are turned in a clockwise direction (as viewed in Fig. 8), they operate through upstanding arms 89 (normally held out bysprings) to move sliding blocks 90 between the upper and lower sections I! and 19 of the crossheads, above referred to.

It will be seen that if the blocks or crosshead interponents 90 of one set are moved between the crosshead sections and the shaft 16 given its single rotation, then only the respective side of the shear operates to out, and if the blocks of both sets are moved in, then both sides of the shear operate. Thus the workmen can eflectivetions, but without having to interrupt progress of the strip stock in the other line.

Any form of control, other than shown, can be used for the selective fabricating mechanism, either for cropping, stitching or unstitching, as

above pointed out. The mechanism of Figs. 7 and 8 may be driven by an electric motor I00, connected to the power shaft 18 in a manner which it is unnecessary to describe in view of such mechanism being well known in the art.

Having in mind that, in order effectively to treat sheet strip stock of such gauge as to require stitching of ends, as against merely hooking the ends together, and to require leveling, a-

pinch-roll-controlled type system is necessary, it will be clear from the above description that greatly increased efli'ciency can be obtained by the use of the system herein disclosed when required to run stock in widths less than of the width capacity of the various mechanisms. The usual strip treatment plant of the class shown can be somewhat speeded up when running such narrow strips, but such speeding up usually results in inferior work because, as in pickling, the stock has to remain in the acid a certain. time. An increase in tank capacity for the sake of speeding up in case of running narrow strips would obviously result in decreased efliciency when having to run wide sheets. By the system and mechanism hereof, narrow strips of such gauge as to necessitate,pinch-roll-controlled units to run them, can'be treated, without requiring disproportionate investment in additional equipment, at efliciencies comparable favorably with those which obtain in case of running single strips of widths which nearly equal the capacity of the apparatus. It will also be seen that by the rearrangement of instrumentalities herein disclosed there can be obtained greatly increased output without requiring expensive building enlargements over the present practice; without sacrifice of the quality of work done; without increased hazards to the workmen; and without danger of damaging the equipment or work., Various, other specific objects hereinbefore set forth have also been accomplished by the present method, system and mechanisms, as will be clear from the above description.

I claim:

1. In a treating apparatus for strip steel, the arrangement of pinch roll mechanism, a stitching mechanism and a shearing mechanism, the latter being adapted for removing stitched portions of the strip; wherein respective side portions of said mechanisms are operable independently of each other in a manner to effect independent feeding, stitching and unstitching of a plurality of individual strips in sid'e-by-side relationship, and, selectively, simultaneously to efl'ect the same operations on a single strip which is sumciently wide to require 'that both side portions of each of the mechanisms operate unitarily.

2. In a pickling apparatus for strip steel, the

arrangement of pinch roll mechanisms at opposite ends of the pickling tanks, cropping mechanism, a stitching mechanism, and a shearing mechanism, the latter being adapted for unstitching; wherein respective side portions of said mechanisms are operable intermittently in-= dependently of each other in a manner to effect independent feeding, cropping, stitching and unstitching of a plurality of individual strips,

1 and, selectively, are operable unitarily andintermittently to effect such operations on a single strip which spans the two portions of each mechanism.

CHARLES CLARKE WALES. 

